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Solid-State Battery With No Anode Has Twice the Energy Capacity of Conventional Batteries

Solid-state batteries promise to elevate Li-Ion batteries to new highs, thanks to the advantages of using solid electrolytes. Scientists at the University of Texas at Austin have discovered that getting rid of the anode can bring important benefits like higher energy capacity and safety.
Prototype anode-free all-solid-state lithium battery 6 photos
Photo: YIXIAN WANG/UNIVERSITY OF TEXAS AT AUSTIN
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Traditionally, Li-Ion batteries are made of two electrodes (the anode and the cathode) that interact through an electrolyte to store and release electricity. The battery’s anode is often comprised of graphite, whereas the cathode is made of metal oxide. They are coated onto metal foils that collect the generated current, usually copper for the anode and aluminum for the cathode. The electrodes in Li-ion batteries interact through a liquid or gel electrolyte, but solid electrolytes are a promising alternative.

Because ceramic electrolytes are more compact than liquids or gels, solid-state batteries can store more energy in the same weight or space. They are also safer because solid electrolytes, made of ceramic materials, are not flammable. Unfortunately, they have a very short lifecycle because batteries develop dendrites, branch-like formations that spread between electrodes. They penetrate through cracks in the solid electrolyte and can produce a short circuit. Nowadays, much of the solid-state battery development aims to solve this problem.

Other studies concentrate on improving solid electrolytes. For instance, sulfide-based electrolytes were considered best for the job because of the bigger energy density they can achieve. Unfortunately, sulfide electrolytes can react with the electrodes, generating compounds that impede the flow of electrons within the battery. Researchers at the University of Texas at Austin have tried to mitigate this by eliminating one of the electrodes from the equation.

They replaced the graphite-based anodes solely with a copper foil collector, boosting the energy density. By eliminating half of the battery material, you also reduce costs. There’s a caveat, though, as the anode-free, solid-state batteries still have the same problem with dendrite formation as they charge and discharge repeatedly. Scientists discovered that a new coating might solve the problem.

By covering the copper current collector with an ultrathin layer of lithium-activated tellurium, they found that lithium metal deposits and dissolves from the copper current collector in a thin, uniform layer. This basically solves the dendrite problem and also improves the battery performance. The new battery can hold 72 percent more energy by weight and 95 percent more energy by volume than commercial lithium-ion batteries.

The best thing is that the tellurium coating can be applied using standard fabrication techniques. This makes it suitable for the mass production of new batteries. The researchers think this might be the missing link for the wide-scale commercialization of anode-free and all-solid-state batteries. There are still many hurdles before the new technology can be scaled up to production. There isn’t a functional prototype battery for now, but the first results are enticing.
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About the author: Cristian Agatie
Cristian Agatie profile photo

After his childhood dream of becoming a "tractor operator" didn't pan out, Cristian turned to journalism, first in print and later moving to online media. His top interests are electric vehicles and new energy solutions.
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